Avalanche Forecast

Issued: Dec 2nd, 2011 9:07AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

A mostly dry northwesterly flow will make its way into the region for saturday, sunday and monday. Winds should remain moderate and northwesterly at ridgetop for the period with freezing levels remaining at or around surface.

Avalanche Summary

No new reports received since last weekend; this may say more to the lack of information from the field and little about field conditions. If you have any observations from the field, please drop us an email: forecaster@avalanche.ca. Information and observations from you can really help.

Snowpack Summary

Snowfall accumulations have not been sufficient to create an avalanche problem below treeline where the snowpack sits at about 30-60cms. Regardless, slopes at higher elevations have been large enough to run down to terrain located well below treeline. In the alpine, and at treeline the snowpack depth generally sits anywhere from 80-120cm with deposits of up to 400 cms on wind-loaded features.Reports suggest that strong to extreme winds in a few parts of the region have stripped west aspects of snow creating wind slabs on lee and cross-loaded aspects in the alpine and at treeline. Many of these new windslabs could be sitting on the reactive October rain crust located a few centimetres above the ground. This rain crust may have weak, overlying facets and is widespread in the alpine and isolated in its distribution at treeline. This is a classic low probability-high consequence scenario where the snow may have been gaining strength, but the consequence of an full-depth avalanche could still be disastrous.It`s worth noting that while the crust-facet combo has been an issue in some areas, it seems to be non-existent in others parts of the region.The 'take home' message is that the region as a whole is data-sparse and extremely variable in terms of snowpack structure. When heading into avalanche terrain, do so gradually and take the time to gather terrain-specific information. Check-out the CAC Field Team`s observations from the Harvey Pass area in our South Rockies discussion forum.Your reports from the field are also highly valued. Any observations can be sent to: forecaster@avalanche.ca

Problems

Wind Slabs

An icon showing Wind Slabs
Expect touchy windslabs in lee or cross-loaded terrain at treeline and in the alpine. Expect redistribution of surface snow and stiffening of current wind slabs with forecast northerly winds,

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Avalanche activity on this layer has decreased, but the problem has not gone away. If triggered, avalanches on this layer could be highly destructive.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Dec 3rd, 2011 8:00AM